Marine organisms, especially soft cerals, sponges and tunicates, provide many secondary metabolites and exhibit a varying degree of biological activity (Reference 13: Faulkner, D. J. Nat.Prod.Reports., 1997, 14, 259-302 and references cited therein). An important family of these metabolites is the alkaloid family; in 1983 it was reported the structure of a marine alkaloid, amphimedine (Reference 14: Schmitz, F. J. et al. J.Am.Chem.Soc. 1983, 105, 4835-4836), which was the first of a new class of marine-derived alkaloids that collectively have come to be known as the xe2x80x9cpyridoacridinesxe2x80x9d. Since then, over 40 additional examples have been published (Reference 1: Molinski, T. F. Chem.Rev. 1993, 93, 1825-1838). The pyridoacridines are highly colored marine derived alkaloids majority based on the 11H-pyrido[4,3,2-mn]acridine skeleton, as shown below: 
A family of remarkable cytotoxic marine pyridoacridine alkaloids is the Shermilamine family (Reference 6: Scheuer, P. J. et al. J.Org.Chem. 1988, 53, 4619-4620. Reference 5: Scheuer, P. J. et al. J.Org.Chem. 1989, 54, 4231-4232. Reference 3: Kashman, Y. et al. J.Org.Chem. 1989, 54, 5335-5337. Reference 12: Barrows, L. R.; Ireland, C. M. et al, J.Med.Chem. 1994, 37, 3819-3827), which structure is showed below: 
Shermilamines were all isolated from tunicates, A and B from Trididemnum sp. and C from Cystodytes sp. 
The present invention provides new pyridoacridines having the following formula (I): 
wherein R is independently selected from the group consisting of hydrogen or bromine.
More particularly, the present invention relates to Shermilamine D (Rxe2x95x90H in formula (I)), extracted and isolated from the tunicate Cystodytes violatinctus. 
Shermilamine D exhibits antitumor activity. In particular, Shermilamine D exhibits antitumor activity against cell lines derived from human solid tumors, such as human lung carcinoma, human colon carcinoma and human melanoma, and, the like, it is active against other tumor cell lines, like leukemia and lymphoma.
The present invention also provides a method of testing a mammal affected by a malignant tumor sensitive to a compound with the formula (I), which comprises administering a therapeutically effective amount of the compound with the formula (I), or a pharmaceutical composition thereof.
The present invention further provides pharmaceutical compositions which contain as active ingredient a compound with the formula (I), as well as process for its preparation.
A further aspect of the invention is a method for preparing the compound Shermilamine D (Rxe2x95x90H in the formula (I)), which comprises extraction and isolation from the tunicate Cystodytes violatinctus.